Effect of Angiotensin Converting Enzyme Inhibition with SQ 14 225 on Blood Pressure in Sheep

Abstract

The effect of intravenous injection of the angiotensin converting enzyme inhibitor SQ 14 225 on blood pressure, heart rate and plasma renin concentration (PRC) was investigated in 15 intact conscious ewes as follows: sodium replete during angiotensin I infusion (n = 4); sodium replete (n = 6); sodium deplete (n = 5); chronic water deprivation (n = 5); AcTH treated sodium replete (n = 6). Following SQ 14 225 mean arterial pressure fell 5 +/- 1 mmHg in sodium replete, 20 +/- 4 mmHg in acutely sodium deplete, 7 +/- 2 mmHg in chronic water deprivation and 6 +/- 2 mmHg in ACTH treated sodium replete sheep. This suggests that the renin-angiotensin system plays no significant role in maintaining the elevated blood pressure of sheep with ACTH induced hypertension. Heart rate rose in all groups except the water deprived animals following SQ 14 225. PRC rose from 5.1 +/- 2.1 pmo1AI/ml plasma/h. to 12.4 +/- 2.0 in sodium replete sheep, from 11.9 +/- 1.0 to 68 +/- 13 in acutely sodium deficient animals, and from 13.3 +/- 4.3 to 32.9 +/- 0.6 in chronically water deprived animals, but showed little change in ACTH treated sheep, falling from 2.3 +/- 0.5 to 1.7 +/- 0.2 pmo1AI/ml plasma/h.